syzbot


divide error in comedi_inc_scan_progress (2)

Status: upstream: reported on 2025/11/05 08:13
Reported-by: syzbot+bb6180f965618f0f7b31@syzkaller.appspotmail.com
First crash: 70d, last: 5d03h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 divide error in comedi_inc_scan_progress 2 2 174d 176d 0/2 auto-obsoleted due to no activity on 2025/11/01 16:46
upstream divide error in comedi_inc_scan_progress comedi 2 74 38d 190d 0/29 upstream: reported on 2025/07/08 17:52
linux-5.15 divide error in comedi_inc_scan_progress 2 2 56d 56d 0/3 upstream: reported on 2025/11/19 00:37
linux-6.1 divide error in comedi_inc_scan_progress 2 1 35d 35d 0/3 upstream: reported on 2025/12/10 08:43

Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 20512 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:comedi_inc_scan_progress+0x1a2/0x430 drivers/comedi/drivers.c:562
Code: b6 0c 19 84 c9 0f 85 b8 01 00 00 03 45 34 4c 8d a5 88 00 00 00 4c 89 e1 48 c1 e9 03 0f b6 0c 19 84 c9 0f 85 c7 01 00 00 31 d2 <41> f7 34 24 41 89 17 45 89 ec eb 0f e8 2d 5d 8a f9 48 bb 00 00 00
RSP: 0018:ffffc90000007c68 EFLAGS: 00010046
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff888078aa6800 R08: ffff888078aa6800 R09: 1ffff92001851200
R10: dffffc0000000000 R11: fffff52001851201 R12: ffff888078aa6888
R13: 0000000000000004 R14: 0000000000000000 R15: ffff888078aa6834
FS:  00005555621e7500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555622025c8 CR3: 0000000065f71000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 comedi_buf_write_samples+0x372/0x5d0 drivers/comedi/comedi_buf.c:646
 aio_iiro_16_cos+0x164/0x1c0 drivers/comedi/drivers/aio_iiro_16.c:69
 __handle_irq_event_percpu+0x276/0x930 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
 handle_edge_irq+0x247/0xb30 kernel/irq/chip.c:831
 generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
 handle_irq arch/x86/kernel/irq.c:240 [inline]
 __common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259
 common_interrupt+0xb4/0xd0 arch/x86/kernel/irq.c:249
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678
RIP: 0010:__sanitizer_cov_trace_switch+0x100/0x120 kernel/kcov.c:-1
Code: f3 48 c1 e3 05 4c 8d 63 28 4d 39 fc 77 9d 49 ff c6 4d 89 33 49 89 4c 1b 08 4d 89 54 1b 10 49 89 7c 1b 18 49 89 54 1b 20 eb 81 <5b> 41 5c 41 5e 41 5f c3 b9 05 00 00 00 48 85 c0 0f 85 52 ff ff ff
RSP: 0018:ffffc90004fdf0f0 EFLAGS: 00000246
RAX: 0000000000000008 RBX: 0000000000000001 RCX: 0000000000000003
RDX: ffffffff813aaa82 RSI: ffffffff8cb9e760 RDI: 0000000000000005
RBP: ffffc90004fdf238 R08: ffff88802c24bc00 R09: 0000000000000008
R10: 0000000000000009 R11: 0000000000000000 R12: ffffc90004fdf1e8
R13: dffffc0000000000 R14: 0000000000000005 R15: ffffffff8f6d87be
 unwind_next_frame+0x742/0x2970 arch/x86/kernel/unwind_orc.c:515
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc+0xb4/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x540 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x592/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x1c3/0x3c0 security/tomoyo/file.c:771
 security_file_open+0x62/0xa0 security/security.c:2854
 do_dentry_open+0x380/0x1500 fs/open.c:916
 do_open fs/namei.c:3640 [inline]
 path_openat+0x274b/0x3190 fs/namei.c:3797
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1421
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3e4458df90
Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 69 95 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 bc 95 02 00 8b 44
RSP: 002b:00007ffe48f48c10 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f3e4458df90
RDX: 0000000000000002 RSI: 00007ffe48f48d20 RDI: 00000000ffffff9c
RBP: 00007ffe48f48d20 R08: 0000000000000000 R09: 00007ffe48f489d7
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000000000af
R13: 00000000000927c0 R14: 00000000001314b2 R15: 00007ffe48f48d20
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:comedi_inc_scan_progress+0x1a2/0x430 drivers/comedi/drivers.c:562
Code: b6 0c 19 84 c9 0f 85 b8 01 00 00 03 45 34 4c 8d a5 88 00 00 00 4c 89 e1 48 c1 e9 03 0f b6 0c 19 84 c9 0f 85 c7 01 00 00 31 d2 <41> f7 34 24 41 89 17 45 89 ec eb 0f e8 2d 5d 8a f9 48 bb 00 00 00
RSP: 0018:ffffc90000007c68 EFLAGS: 00010046
RAX: 0000000000000001 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff888078aa6800 R08: ffff888078aa6800 R09: 1ffff92001851200
R10: dffffc0000000000 R11: fffff52001851201 R12: ffff888078aa6888
R13: 0000000000000004 R14: 0000000000000000 R15: ffff888078aa6834
FS:  00005555621e7500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555622025c8 CR3: 0000000065f71000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
   0:	b6 0c                	mov    $0xc,%dh
   2:	19 84 c9 0f 85 b8 01 	sbb    %eax,0x1b8850f(%rcx,%rcx,8)
   9:	00 00                	add    %al,(%rax)
   b:	03 45 34             	add    0x34(%rbp),%eax
   e:	4c 8d a5 88 00 00 00 	lea    0x88(%rbp),%r12
  15:	4c 89 e1             	mov    %r12,%rcx
  18:	48 c1 e9 03          	shr    $0x3,%rcx
  1c:	0f b6 0c 19          	movzbl (%rcx,%rbx,1),%ecx
  20:	84 c9                	test   %cl,%cl
  22:	0f 85 c7 01 00 00    	jne    0x1ef
  28:	31 d2                	xor    %edx,%edx
* 2a:	41 f7 34 24          	divl   (%r12) <-- trapping instruction
  2e:	41 89 17             	mov    %edx,(%r15)
  31:	45 89 ec             	mov    %r13d,%r12d
  34:	eb 0f                	jmp    0x45
  36:	e8 2d 5d 8a f9       	call   0xf98a5d68
  3b:	48                   	rex.W
  3c:	bb                   	.byte 0xbb
  3d:	00 00                	add    %al,(%rax)

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/09 14:08 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan divide error in comedi_inc_scan_progress
2025/11/20 03:06 linux-6.6.y 0a805b6ea8cd 26ee5237 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan divide error in comedi_inc_scan_progress
2025/11/05 08:13 linux-6.6.y 0a805b6ea8cd a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan divide error in comedi_inc_scan_progress
* Struck through repros no longer work on HEAD.